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I have 4 RAM slots on the motherboard P5K. At the moment I have two 1GB RAM modules and two 2GB RAM modules. Everything is working fine.

Can I buy one 4GB module and put it instead of the 1GB module?

Another question, can I mix MHz values, like that I have two 667MHz modules and two 1066MHz modules? Is this dangerous for the comp?

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Not all motherboards of the time your referring to would handle 4G single modules , it was 2G modules by 4 . there are many versions of the PK5 board, find your version on the asus site and check the specs the manuel, and the memory compatability list there, before attempting 4g modules. – Psycogeek Jan 24 '12 at 10:23
up vote 8 down vote accepted


However, having paired modules (e.g. 2x2GB) will more than likely give you better performance as the memory can run in Dual Channel mode rather than Single Channel. You won't get exactly double the transfer rate as there are overheads involved but it should be close.

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This motherboard does not support DDR3 :). But thanks for the info – JoeM Jan 24 '12 at 9:26
dual channel counts for DDR2 as well. Ram slots of the same colour are the same channel, and if both are filled with identical ram, it works better than mismatched ram or a single stick – Journeyman Geek Jan 24 '12 at 9:32

Probably, with some caveats.

All the RAM will run at the timing and latency of the worst stick of RAM there. You may also need to check if your BIOS/EFI supports that RAM size - some older versions may not support larger RAM sizes, and may need an update, and the total amount of RAM may be limited in the same fashion.

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Oh, so it's useless to buy the RAM with larger latency. Thanks – JoeM Jan 24 '12 at 9:29
lower latency is better iirc, and higher speed. ANY ram you buy will be as good as the worst ram you have in terms of both in the system. – Journeyman Geek Jan 24 '12 at 9:31

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